JPH05335179A - Temperature compensating dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To obtain temperature compensating dielectric porcelain composition whose main component is represented y a formula, aCaNb2 O6-bZnNb2O5-cZNO- dCaTiO3, where cheap metal can be used as inner electrode material. CONSTITUTION:CaCo3, ZnO, Nb2O5, and TiO2 are weighed corresponding to compositions, mixed by a hot-type ball mill, the dried up, and calcined for the formation of main raw material. The obtained material serves as temperature compensating dielectric magnetic composition whose main component is represented by a formula, ACaNb2O6-bZnNb2O5-cZNO-dCaTiO3. In the formula, a, b, c, and d are molar fractions and so set as to satisfy formulas, 0.10<=a<=0.60, 0.05<=b<=0.60, 0.15<=c<=0.75, 0.01<=d<=0.2, and a+b+c+d=1. By this setup, a temperature compensating porcelain capacitor, whose electrostatic capacity has the absolute value of temperature coefficient below 60ppm/ deg.C and which is below 0.2% in dielectric loss tan delta and above 1X10<13>OMEGAcm in resistivity at a temperature of 20 deg.C, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-compensating dielectric porcelain composition, and more particularly to a temperature-compensating dielectric porcelain composition used as a material for a dielectric porcelain of a multilayer capacitor.

[0002]

2. Description of the Related Art Heretofore, as a dielectric ceramic composition for temperature compensation of this type, there has been a MgTiO ₃ --CaTiO ₃ system composition.

[0003]

However, MgT
The porcelain using the iO ₃ —CaTiO ₃ composition has a high firing temperature of 1300 ° C. or higher, and has the property of being reduced to a semiconductor when fired under a neutral or reducing low oxygen partial pressure. Was there. Therefore, when such a composition is used as a material for a multilayer capacitor,
As a material for the internal electrodes, a noble metal such as Pt or Pd which is not melted at the sintering temperature of the dielectric ceramic material and is not oxidized even under a high oxygen partial pressure that does not turn the dielectric ceramic material into a semiconductor must be used. There wasn't. Therefore, it has been a major obstacle to lowering the price of manufactured multilayer capacitors.

In order to solve the above problems, it has been desired to use an inexpensive base metal such as Ni or Cu as a material for the internal electrodes. However, when such a base metal is used as a material for the internal electrode and fired under the conventional oxidizing atmosphere, the electrode material is oxidized or melted. Therefore, since such a base metal is used as a material for the internal electrode, it does not become a semiconductor even when fired at a low temperature in a neutral or reducing atmosphere with a low oxygen partial pressure, and is sufficiently used as a dielectric material for a capacitor. There has been a need for a dielectric material having a high specific resistance and excellent dielectric properties.

A dielectric ceramic composition for solving this kind of problem is disclosed in JP-A-1-102806. Since this dielectric porcelain composition can be fired in a neutral and reducing atmosphere with a low oxygen partial pressure,
By using this, a temperature compensating multilayer capacitor having a base metal such as Ni or Cu as an internal electrode can be manufactured.
However, the dielectric ceramic composition disclosed in JP-A-1-102806 can solve the above problems with respect to the firing temperature and the temperature coefficient of the dielectric constant, but has a dielectric constant ε of 1 or less.
It is as low as 0, and the dielectric loss tan δ is 0.
It is as large as 05% or more.

Therefore, the main object of the present invention is to achieve the following effects in a neutral or reducing atmosphere with a low oxygen partial pressure:
Sintered at 200 ° C. or lower and not reduced, dielectric constant ε is 20 or more, and absolute value of temperature coefficient of capacitance is 60.
ppm / ° C or less, dielectric loss tan δ is 0.02% or less,
The specific resistance at 20 ° C. is 1 × 10 ¹³ Ωcm or more,
It is an object of the present invention to provide a dielectric ceramic composition for temperature compensation, which can use an inexpensive metal such as Cu as a material for internal electrodes.

[0007]

The present invention is directed to aCaNb
_{2 O 6 -bZnNb 2 O 6 -cZnO} -dCaTiO 3
A temperature-compensating dielectric porcelain composition having a composition represented by as a main component, wherein a, b, c and d are each a mole fraction,
0.10 ≦ a ≦ 0.60, 0.05 ≦ b ≦ 0.60,
The dielectric ceramic composition for temperature compensation is in the range of 0.15 ≦ c ≦ 0.75 and 0.01 ≦ d ≦ 0.20, and satisfies the relationship of a + b + c + d = 1. Furthermore, the main component 100
With respect to parts by weight, B ₂ O ₃ , SiO ₂ , L as auxiliary components
0.1 to 20 parts by weight of at least one metal oxide selected from i ₂ O may be added.

[0008]

According to the present invention, sintering is carried out at a low temperature of 1200 ° C. or less in a reducing atmosphere, the absolute value of the temperature coefficient of capacitance is 60 ppm / ° C. or less, and the dielectric loss tan.
δ is 0.02% or less, and the specific resistance at 20 ° C. is 1
A dielectric ceramic composition for temperature compensation having a characteristic of × 10 ¹³ Ωcm or more can be obtained. Therefore, if this temperature-compensating dielectric ceramic composition is used as a material for a laminated capacitor, a base metal such as Cu can be used as a material for internal electrodes. Therefore, it is possible to eliminate the increase in the cost of the electrodes due to the increase in capacity of the multilayer capacitor, and it is possible to provide a low-cost multilayer capacitor. Further, since the dielectric loss tan δ is small, it can be used as a material for microwave LC filters, RF modules, and the like.

The above objects, other objects, features and advantages of the present invention will become more apparent from the detailed description of the embodiments below.

[0010]

EXAMPLES First, CaNb ₂ O ₆ , ZnNb ₂ O ₆ , C
CaCO ₃ , ZnO, Nb as a starting material of aTiO _3
2 O ₅ and TiO ₂ were prepared. These raw materials are weighed according to each composition, wet-mixed in a ball mill and then dried,
It was calcined at 0 to 1200 ° C. for 3 hours to obtain a raw material of the main component.

Materials containing at least one kind of metal oxide among B ₂ O ₃ , SiO ₂ and Li ₂ O were weighed so that the compounding ratios shown in Table 1 were obtained, and these were wet mixed by a ball mill. After crushing, it was evaporated to dryness and melted at 1000 ° C. in a natural atmosphere. Furthermore, 1 with a ball mill
After wet pulverization to a size of less than μm, it was evaporated to dryness to obtain subcomponents.

[0012]

[Table 1]

The raw materials thus obtained were weighed so as to have the composition shown in Table 2 and wet-mixed in a ball mill for 16 hours. Then, 5 parts by weight of a vinyl acetate binder was added as a binder and wet-mixed in a ball mill. A mixture was obtained.

[0014]

[Table 2]

Further, after evaporating and drying this mixture,
The powder was sized to obtain a powder raw material. 2 to the obtained powder raw material
Pressurized with a pressure of n / cm ² , diameter 20 mm, thickness 1.0
It was molded into a disc having a size of mm to obtain a molded product. This molded product was placed in an alumina box containing zirconia powder as floor powder, and the vinyl acetate binder was burned for 2 hours at 500 ° C. in a natural atmosphere. After that, the volume ratio of H ₂ : N ₂ =
In a reducing atmosphere of 3: 100, the molded product is 900
A device was obtained by firing at ˜1350 ° C. for 2 hours. In-Ga alloy is applied to both surfaces of the obtained device to form electrodes,
A capacitor as a sample was manufactured.

With respect to the obtained sample, the dielectric constant ε, the dielectric loss tan δ, the temperature coefficient of capacitance α (ppm / ° C.), 2
The specific resistance ρ ₂₀ (Ωcm) at 0 ° C. was measured. In addition,
The dielectric loss tan δ is 1 MHz, 1 Vrms,
It was measured under the condition of 20 ° C. Also, the temperature coefficient T of the capacitance
C (ppm / ° C.) was obtained by the following formula from the electrostatic capacitance C _{20 at 20} ° C. and the electrostatic capacitance C _{85 at} 85 ° C.

[0017]

[Equation 1]

Furthermore, the specific resistance at 20 ° C. ρ ₂₀ (Ωc
m) was obtained from the value of the current flowing when a DC voltage of 500 V was applied at 20 ° C. The results are shown in Table 3. In Tables 2 and 3, those marked with * are outside the scope of the present invention, and the others are within the scope of the present invention.

[0019]

[Table 3]

Next, the reason why the numerical values of the main component and the sub-components of the temperature compensating dielectric ceramic composition of the present invention are limited will be explained. As shown in sample number 6, the main component aCaNb ₂
When c of O ₆ -bZnNb ₂ O ₆ -cZnO-dCaTiO ₃ is larger than 0.75, the dielectric loss tan δ is 0.
Is greater than 02%, the absolute value of the temperature coefficient of capacitance is greater than 60 ppm / ° C, and the specific resistance is 1 × 1.
Since it is less than 0 ¹³ Ωcm, it is not preferable. When the main component a is smaller than 0.10 as in Sample No. 7, the specific resistance is less than 1 × 10 ^13, which is not preferable. When the main component c is smaller than 0.15 as in Sample No. 8, the firing temperature exceeds 1200 ° C., and the absolute value of the temperature coefficient of capacitance becomes larger than 60 ppm / ° C., which is not preferable. When the main component b is less than 0.05 as in sample number 9, the firing temperature exceeds 1200 ° C., the absolute value of the temperature coefficient of capacitance is greater than 60 ppm / ° C., and the dielectric loss tan δ is 0. It is not preferable because it becomes larger than 0.02%. When the main component d is larger than 0.20 as in Sample No. 11, the firing temperature exceeds 1200 ° C., and the absolute value of the temperature coefficient of capacitance becomes larger than 60 ppm / ° C., which is not preferable.

When the addition amount of the sub-component of the A series shown in Table 1 is more than 20 parts by weight, as in sample No. 14, the dielectric constant ε
Is less than 20, and the dielectric loss tan δ is 0.02%
It becomes larger, which is not preferable. When the amount of the B-series auxiliary component shown in Table 1 is more than 20 parts by weight as in Sample No. 17, the dielectric constant ε is less than 20, and the dielectric loss ta
It is not preferable because nδ is greater than 0.02%, the absolute value of the temperature coefficient of capacitance is greater than 60 ppm / ° C., and the specific resistance is less than 1 × 10 ¹³ Ωcm.

On the other hand, according to the present invention, sintering is performed at a low temperature of 1200 ° C. or less in a reducing atmosphere, the absolute value of the temperature coefficient of the electrostatic capacitance is 60 ppm / ° C. or less, and the electrostatic capacitance tan δ is 0. It is possible to obtain a temperature-compensating dielectric ceramic composition having a characteristic of 0.02% or less and a specific resistance at 20 ° C. of 1 × 10 ¹³ Ωcm or more. Therefore,
If this temperature-compensating dielectric ceramic composition is used as a material for a laminated capacitor, a base metal such as Cu can be used as a material for internal electrodes. Therefore, it is possible to eliminate the increase in the cost of the electrodes due to the increase in capacity of the multilayer capacitor, and it is possible to provide a low-cost multilayer capacitor. Further, since the capacitance tan δ is small,
It can be used as a material for LC filters and RF modules for microwaves.

Claims (2)

[Claims] 1. A CaNb ₂ O ₆ -bZnNb ₂ O _6-
A temperature-compensating dielectric porcelain composition having a composition represented by cZnO-dCaTiO ₃ as a main component, wherein a, b, c, and d are each a mole fraction, and 0.10 ≦ a ≦ 0.60 0. 0.05 ≦ b ≦ 0.60 0.15 ≦ c ≦ 0.75 0.01 ≦ d ≦ 0.20, satisfying the relationship of a + b + c + d = 1,
Dielectric ceramic composition for temperature compensation. 2. 0.1 to 20 parts by weight of at least one metal oxide selected from B ₂ O ₃ , SiO ₂ , and Li ₂ O is added as a subcomponent to 100 parts by weight of the main component. The dielectric ceramic composition for temperature compensation according to claim 1.